A construction of UD $k$-ary multi-user codes from $(2^m(k-1)+1)$-ary codes for MAAC

Abstract

In this paper, we proposed a construction of a UD $k$-ary $T$-user coding scheme for MAAC. We first give a construction of $k$-ary $T^{f+g}$-user UD code from a $k$-ary $T^f$-user UD code and a $k^{\pm }$-ary $T^g$-user difference set with its two component sets ${\mathcal{D}}^{+}$ and ${\mathcal{D}}^{-}$ {\em a priori}. Based on the $k^{\pm }$-ary $T^g$-user difference set constructed from a $(2k-1)$-ary UD code, we recursively construct a UD $k$-ary $T$-user codes with code length of $2^m$ from initial multi-user codes of $k$-ary, $2(k-1)+1$-ary, \dots, $(2^m(k-1)+1)$-ary. Introducing multi-user codes with higer-ary makes the total rate of generated code $\mathcal{A}$ higher than that of conventional code.